1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display module having a structure for protecting lead wires of a backlight device from being damaged and a method of fabricating the same.
2. Discussion of the Related Art
Flat panel display devices are increasingly being used in portable devices and household appliances because of their advantageous characteristics of thin profile, lightness, and low power consumption. There are many types of flat panel display devices, such as plasma display panels (PDPs), field emission displays (FEDs), and the widely used liquid crystal display (LCD) devices. While the principles of the present invention are generally applicable to all such displays, it will be discussed with respect to an LCD device used in a portable computer, a computer monitor, or a television as an example.
LCD devices use optical anisotropy and polarization properties of liquid crystal molecules to generate a desired image. In particular, liquid crystal molecules can be aligned in a specific orientation, which can be controlled by applying an electric field across the liquid crystal molecules. Due to the optical anisotropy, incident light is refracted according to the orientation of the liquid crystal molecules, thereby generating the desired image.
In general, a liquid crystal module (LCM) for an LCD device includes a liquid crystal panel having upper and lower substrates with a liquid crystal material interposed therebetween, a backlight assembly having a lamp, a light reflector, a light guide plate and a plurality of optical sheets, a main support supporting the liquid crystal panel and the backlight assembly, and top and bottom cases protecting and accommodating the liquid crystal panel and the backlight assembly.
FIG. 1 is an exploded perspective view illustrating a liquid crystal display module according to the related art. In FIG. 1, a liquid crystal module 2 includes a main support 60, a top case 70, and a bottom case 80. The main support 60 is coupled to the bottom case 80 such that the main support 60 is protected from being twisted and wrinkled. In particular, the bottom case 80 is generally formed of a metallic material, such as stainless steel, and the main support 60 is generally formed of a plastic material.
In addition, a backlight assembly 23 having a lamp 29 is supported by the main support 60 and the bottom case 80. The backlight assembly 23 also includes a reflector 23a, a light guide plate 23b, a first diffusing/protecting sheet 23c, first and second prism sheets 23d and 23e, and a second diffusing/protecting sheet 23f, which are layered in sequence between the main support 60 and a liquid crystal panel 14. In particular, the lamp 29 is disposed at one side of the light guide plate 23b. The lamp 29 generally is a cold cathode fluorescent lamp (CCFL) and connects to a connector 7 outside of the liquid crystal display module 2.
Further, the liquid crystal (LC) panel 14 is connected to a printed circuit board (PCB) 25 by a flexible film. When the liquid crystal module 2 is assembled, the PCB 25 is folded onto the bottom of the main support 60, and the top case 70 is coupled to the bottom case 80. As a result, the top case 70 and the main support 60 hold and retain the liquid crystal panel 14 and the backlight assembly 23 together. Although not shown, the main support 60 may be alternatively disposed adjacent to the liquid crystal panel 14.
The backlight assembly 23 can be a direct-type backlight device or an edge-type backlight device. In a direct-type backlight device, a light source is generally disposed underneath the light guide plate. Light generated from the light source is reflected onto a back surface of the liquid crystal panel using the reflector and diffused using a diffuser sheet. Thus, the direct-type backlight device can be used for the wall-mounted television requiring a high brightness. However, the direct-type backlight device has disadvantages, such as being relatively thick, consuming significant power, and having a high fabrication cost.
In comparison, an edge-type backlight device receives light through one side of a plate-shaped light guide comprised of a transparent acryl resin. The edge-type backlight device directs the received light to a light outputting surface of the light guide plate such that it illuminates the back of a liquid crystal panel. In order to improve light efficiency, an optical reflective plate or an optical reflective film is often provided on the opposite side of the light output surface of the light guide plate. To make the light output uniform, a light diffuser sheet is often provided at the light output surface of the light guide plate. The edge-type backlight device is lightweight, has a thin profile, and consumes little power. Thus, the edge-type backlight device is highly suitable for portable computers.
FIG. 2 is a view of an illuminating section of a backlight device according to the related art. In FIG. 2, the illuminating section 26 of a backlight device includes the lamp 29, a lamp holder 31, a lamp housing 33, and wires 27. The lamp housing 33 reflects light emitted from the lamp 30 toward a desired direction, and the wires 27 include a power wire 27a and a ground wire 27b. The power wire 27a and the ground wire 27b are disposed between the connector 7 and the lamp 29. In particular, the power wire 27a is soldered to one end of the lamp and the ground wire 27b is soldered to another end of the lamp 29. Further, the lamp holder 31 covers the solder connections between the lamp 29 and the power and ground wires 27a and 27b. Although not shown in FIG. 2, the connector 7 is connected to an inverter power supply circuit such that the wires 27 supply power to drive the lamp 29.
FIG. 3 is a partially enlarged perspective view of a liquid crystal module according to the related art. As shown in FIG. 3, when a liquid crystal module 50 is assembled, there exists a wire outlet portion near one of its corner portions to allow the wires 27 that are connected to the lamp 29 be extended to the outside of the liquid crystal module 50. In particular, a top case 65 and a bottom case 67 are coupled to each other and hold a liquid crystal panel and a backlight assembly therebetween. A wire holder 90 having an opening 92 is disposed at the wire outlet portion, such that the wires 27 pass through the opening 92 to exit out of the liquid crystal panel 50. Although not shown in FIG. 3, the wires 27 are connected to the connector 7 (as shown in FIG. 2).
The top and bottom cases 65 and 67 are generally made of a metallic material through a molding die process, and they may have cutting burrs at their edges after the press molding. The burrs formed at the edge portions of the top and bottom cases 65 and 67 may damage the coated material of the wires 27 and then may cause a short between the wires 27. Therefore, the wire holder 90 is provided at the wire outlet portion between the top and bottom cases 65 and 67 to protect the wires 27.
FIG. 4 is an exploded perspective view of the liquid crystal module shown in FIG. 3, and the liquid crystal panel and the backlight assembly are not depicted in FIG. 4 for the purpose of simplifying the figure. In addition, although not shown in FIG. 4, the wires 27 are pulled through the opening 92 of the wire holder 90 (as shown in FIG. 3) before the wire holder 90 is inserted between the top and bottom cases 65 and 67. As shown in FIG. 4, the top and bottom cases 65 and 67 respectively have protrusions 65a and 67a along one of their edges.
When assembling the liquid crystal module, the wire holder 90 is first mated with the protrusion 67a of the bottom case 67 by sliding into it. Thereafter, a main support 58 on which the liquid crystal panel and the backlight assembly are disposed is laid onto the bottom case 67 while the wires are inserted through the opening 92. Then, the top case 65 is coupled to the bottom case 67. As a result, the wire holder 90 is supported and fastened by the protrusions 65a and 67a of the top and bottom cases 65 and 67.
However, since the wire holder 90 is to be coupled to the bottom case 67 first, additional time is required to carefully put and slide down the wire holder 90 into the protrusion 67a, thereby increasing assembling time and reducing labor efficiency. Moreover, because the wire holder 90 is a separate element from the top and bottom cases 65 and 67, fabrication cost is increased.